Manchester City are in a very strong position, both financially and with their playing squad. That said, there are always improvements and tweaks to be made, and recent history shows us they're quite disciplined when it comes to wages and contract lengths.
Kevin De Bruyne's extension, for example, was for just two seasons -- though it will take him through to the age of 34. Pep Guardiola has made it clear he's not going to force players to stay (or, if they leave it will be on the club's terms) and the transfers of Raheem Sterling, Oleksandr Zinchenko and Gabriel Jesus show City practice what they preach.